Fire resistant sheet material



Patented Sept. 23, 1952 FIRERESISTANT SHEET MATERIAL HubertLeopoldBccher, Trenton, N. J.,-as'signor to Homasote Company,Incorporated, Fernwood, N. J a'corporation of New Jersey No Drawing.Application J une 27,1947, Serial No. 757,663

.1 Myjinvention relates .to 'felted .fibrous sheet material and tomethods .ofjproducing the same 'andrelates particularly ..to-.productshaving improvedfireresistant properties.

"Fibrous.sheetrmaterial such as wallboard and the like, have been 1produced. heretofore by the use .of fibrous materials'land binders.However, whenlthe fibrousinaterialcor the binder, or both, are.Oforganic origin the sheet material is relatively-inflammableand doesnot withstand the firectests ,prescribediinmany building codes. One

.particularly .severe Jfire test is that referred to as the "cribtestf:and described in the Proceedings of the-Americansociety lior IestingMaterials, vol. ll, page-238 (1941). .According to this test pieces ofthe imaterial to ebe tested are arranged in. spacedrelation. and insuccessive tiers toforma crib or chimney-like arrangement and a Meekerburner is placed beneath the assembly .for a-period of threeminutes. Onremoval of if the burner the materialashould cease to burn or glowwithina prescribed time, generally one minute or-less. 1

Numerous eiiorts have been made to render fibrous-sheet materialsfireresistant'by treating or impregnating the sheet withfire retardingagents such as 1 aluminum\ sulfate, borax, ammonium phosphateor thelike.However, in order for such agentstobe applied effectively andeconomically to sheet material by impregnation or otherwise they mustnecessarily be soluble in water and they therefore tend to leach out ofthe finished product if itflis exposed to the weather or to'excessmoisture. Moreover, such agents fre- Furthermore, such sheets are notgenerally adaptedjor use in'the interior of buildings and cannot besanded or polished topresent an attractive finish and do not lendthemselves to decoration by the use of paint, wallpaper or the like.

In accordance with'my invention'a new type of fire resistant sheetmaterial is produced which is relatively light in weight; as comparedwith 'cement-"asbestosor gypsum sheets and preferably has 'a specificgravity of less than 1.0 and i 6 Claims. (Cl. 92-3) generally about 0.6to 0.7. These products contain fibrous materialwhich maybe wholly or inlarge part composed of vegetable fibers and are further characterized byimproved impact and tensile strength which permits easy nailing of thematerial in place, and by their ability to be finished, sanded ormachined to produce an attractive finish and one capable of receivingand holding paint, wallpaper and other decorative materials.

These advantages'are obtained by the use of a noveltype of fireresistant and fire suppressing binder for'the fibrous material. A'hereinafter described the principal active constituent of the binder isan amine type resin. In most'instances the amine type resin is iisedincombination with a chlorinated resin and His further found that by usinga metal hydrate in combination with the resin, fire resistant propertieof the finished product arematerially increased. Moreover, the preferredmethod of producing fire resistant sheet material hereafter describedserves to insure substantially uniform distribution of the fireresistant agent throughout the product's'o that even though'the surfaceof the sheet is'removed by sanding or finishing operations the productwill retain its fire resistant qualities.

One of the objects of my invention is to produce a novel'type .offireresistant fibrous sheet material.

Another object of my invention is to produce a fire resistant feltedfibroussheet containing a binder having an amine type" resin as itsprincipal active constituent.

A further object of my invention is to provide fire resistant sheetmaterial wherein the fire resisting agent is largely resinous incharacter and distributed substantially uniformly throughout theproduct.

Another object of my-invention is to provide a fire resistant'sheethaving: a specific gravityless than 1.0.

Another object .of my invention is s to rovide novel methods forproducinglfire resistant'fibrous products.

These and other objects and features of my invention willappear fromthe-following description thereof in" which typicalj products andmethods are described for the purpose of indicating the nature of. myinventiombutwithout intending to limit the scope of the inventionthereby.

In producing products-in accordance with my invention any suitabletypeof fibrous material may be employed and when producing-a light Weightsheet part or all of the fibrous materia used is generally vegetablefiber, such as news fiber. However, cotton fibers, cotton linters, wooland wood or rag fibers as well as asbestos or mineral fibers may beemployed. The fiber employed in the product is generally equal in weightto from about 40 to 60% by weight of the total composition, but theseproportionsmay be varied considerably depending upon the type and weightof the sheet material or product desired.

The principal active constituent of the binder employed in accordancewith my invention i an amine type resin which preferably is employed incombination with a chlorinated resin and a metal hydrate such asaluminum hydrate. Among the amine resins which may be used are urea,dimethylolurea, monomethanolurea, urea-formaldehyde combinations,melamine, guanidine and the like. The urea resin may be prepared from 1dimethylolurea and urea in equal molecular proportions. In thealternative the urea resin may consist of molar equivalents of urea andformaldehyde. The amine type resin is preferably introduced into theproduct in the form of resin forming constituents whereby the resin isactually produced by polymerization of the constituents during thedrying of the sheet fibrous composition.

The amount of the binder present in the finished product generallyequals from about 40 to 60% by weight of the finished product. At leastone-third or more of the binder consists of amine in carrying out thecrib test referred to above.

In addition to the amine resin the binder preferably contains hydratedalumina and chlorinated resin. The latter constituents materiallyincrease the eifectiveness of the binder as a fire retarding agent andwhen such a chlorinated resin is used the amount of the amine type resinemployed may generally be reduced. 'I'he hydrated alumina appears tocatalyze the decomposition reaction of the amine resin on heating andserves to insure the formation of fire dampening fumes or firesuppressing agents. The acid effect of the chlorinated resin in theproduct appears to be overcome by the influence of or possibly bycombination with, the amine type resin used and it seems probable thatammonium chloride fumes are developed and serve as a fire suppressingagent on decomposition of the amine resin and the chlorinated resin incombination. However, I do not wish my invention to be limited'by anyparticular theory of operation.

The chlorinated resins which may be used may be chlorinated paraifins ofvarying chlorine content. Chlorinated diphenyl, polyvinyl chloride,chlorinated rubber and the like also may be used, although I prefer toemploy chlorinated paraffin having a relatively high chlorine content,say 70% chlorine. The amount of chlorinated resin employed in thecomposition may be'varied considerably, but in view of the cost of suchresins it is generally preferable to use as little of this resin asrequired to insure the desired fire resistant properties of the finishedproduct.

4 Ordinarily, this resin amounts to'from about 4 to 12% by weight of theproduct.

The metal hydrate used is preferably aluminum hydrate and is used invarying amounts equal to from about 12 to by weight of th finishedproduct. r v

A typical; product embodying my invention has the following composition:7

When produced as hereinafter described, the product is in the form of a'felted fibrous sheet which ceases to burn or glow within about secondsafter removal of the burner in carrying out the crib test. The producthas a specific gravity between 0.6 and 0.7 and it may be sanded ortooled to present a very attractive finish. Its tensile strength andmodulus of rupture are high and the sheet possesses excellent nailholding properties and an impact resistance exceeding that ofcement-asbestos sheets of like thickness.

In producing products in accordance with my invention,'variousalternative methods maybe employed. Thus, for example, chlorinatedparaffin and aluminum hydrate may be added to a fibrous pulp and theresulting mixture may be sheeted and dried after which the dried sheetmay beimpregnated with the amine type resin forming constituents.Subsequent-drying of the sheet serves to cause the resin formingconstituents to polymerize producing a fibrous sheet which issuificiently fire resistant to withstand the crib test referred toabove.

In the preferred form of producing sheets in accordance with myinvention the chlorinated resin and metal hydrate are mixed with thefibrous pulp. The material is then wet pressed until it contains notover about of water. The material is then redispersed in a solutioncontaining the amine resin forming constituents and is thereaftersheeted, pressed and dried. In this way, the fire resisting binder isdistributed substantially uniformly througout the sheet and a strongfire resistant product is produced.

In order to illustrate typical procedure in carrying out these methods,the following examples are cited:

Example 1 72 pounds of paper suchas news print are mixed with 3600pounds of water in a pulper and an emulsionv containing9 pounds ofchlorinated parafiin chlorine) are added together with The wet pulp fromthe pressing operation is passed to av mixer where it is disintegratedand redispersed in 2895 lbs. of a solution containing the resin formingchemicals so as to produce a batch of 3000 lbs. of mix containing ti /2%of solids. The solution is produced by adding 500 lbs. of dimethylolureaand 450 lbs. of urea to 1945 lbs. of water. The mixture is agitatedthoroughly and passed to sheet forming and pressing equipment where theproduct is subjected to a pressure of 50 lbs. per square inch. Theproduct weighs 288 lbs. and contains approximately 50% by weight ofwater, whereas approximately 2700 lbs. of the liquid pressed out of thesheet is returned for use in the treatment of an additional batch ofmaterial. The pressed sheet is then passed to a drier where it issubjected to temperatures about 212 F. until the dry weight of thefinished product is approximately 150 lbs. During the drying operationthe resin forming constituents added after redispersion of the materialare caused to polymerize forming a urea resin which is distributed withthe chlorinated paraffin and hydrated alumina throughout the sheet.

This product when subjected to the crib test described above ceases toflame or glow in less than 30 seconds with a loss in weight of less than30%. The product has a density of approximately 0.6, a tensile strengthof 1000 to 1300 lbs. per square inch, 2. modulus of rupture of 1800 to1825 lbs .per square inch and a water absorption of from 12 to 20%. Theproduct may be sanded or tooled to present an attractive finishedsurface and possesses considerably greater resistance to impact thansheets of corresponding thickness formed of cement'asbestoscompositions.

Example 2 Instead of redispersing the thickened and dehydrated pulpcontaining the chlorinated paraffin and hydrated alumina as produced inExample 1, the material may be sheeted and dried and thereafterimpregnated with a solution of the amine resin forming constituents. Forthis purpose 150 lbs. of a solution containing 95 lbs. of water, 29 lbs.of dimethylolurea and 26 lbs. of urea may be applied to the dried andpressed sheet in an impregnator to produce a product having a wet weightof 250 lbs. This sheet may then be passed to a drier where it issubjected to temperatures above 212 F. whereby 107 lbs. of water areevaporated and a finished product weighing 143 lbs. is produced.

This product, like that previously described, withstands the crib testfor resistance to combustion and has a specific gravity between 0.6 and0.7 whereas it may be sanded or finished to present a smooth attractivesurface.

It will be apparent from the foregoing description that the compositionof products embodying my invention may be varied considerably dependingupon the properties and characteristics desired in the finished product.It will also be apparent that various modifications may be made in themethod of producing products embodying my invention; In view thereof itshould be understood that the particular compositions and methods ofprocedure described above are intended to be illustrative only and arenot intended to limit the scope of my invention.

I claim:

1. A fire-resistant felted fibrous sheet material containing from 40 to60% by weight of fiber, from. 2,0 to 40% by weight of amine resin, from4 6 to 12% by weight of a chlorinated resin, and from 12 to 20% byweight of hydrated alumina.

2. A fire-resistant felted fibrous sheet material containing from 40 to60% by weight of fiber, from 20 to 40% by weight of amine resin, from 4to 12% by weight of chlorinated resin, and from 12 to 20% by weight ofhydrated alumina, said fiber being predominantly organic fiber and thesheet material having a specific gravity not exceeding 1.0.

3. A fire-resistant felted fibrous sheet material containing from 40 to60% by weight of fiber, from 20 to 40% by weight of urea resin, from 4to 12% by weight of chlorinated resin, and from l2,to 20% by weight ofhydrated alumina.

4. A fire-resistant felted fibrous sheet material containing from 40 to60% by weight of fiber, from 20 to 40% by weight of urea resin, from 4to 12% by weight of chlorinated parafiin and from 12 to 20% by weight ofhydrated alumina.

5. A fire-resistant felted fibrous sheet material having substantiallythe following composition:

Percent Fibrous material 48 Amine resin 30 Chlorinated resin 5.5Hydrated alumina 16 6. A fire-resistant felted fibrous sheet materialhaving substantially the following composition:

Per cent Organic fibers 48 Urea resin 30 Chlorinated paraffin 5.5Hydrated alumina 16 HUBERT LEOP'OLD BECHER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1 147,833 Fell Feb. 24, 18741,907,711 Becher May 9, 1933 2,030,653 Quinn Feb. 11, 1936 2,375,245Pretzel May 8, 1945 2,410,078 Kellgren Oct. 29, 1946 2,413,163 BaconDec. 24, 1946 2,416,447 Laughlin Feb. 25, 1947 2,427,997 White Sept. 23,1947 2,439,396 Leatherman Apr. 13, 1948 2,462,803 Campbell et al Feb.22, 1949 FOREIGN PATENTS Number Country Date 821,840 France Dec. 14,1937 OTHER REFERENCES Hackhs Chemical Dictionary, 3d ed. (1944), pages615, 733, 734.

Flameproofing Textile Fabrics by Little, published by ReinholdPublishing Corp, New .York, pages 22 2 1 .1 47).

1. A FIRE-RESISTANT FELTED FIBROUS SHEET MATERIAL CONTAINING FROM 40 TO60% BY WEIGHT OF FIBER, FROM 20 TO 40% BY WEIGHT OF AMINE RESIN, FROM 4TO 12% BY WEIGHT OF A CHLORINATED RESIN, AND FROM 12 TO 20% BY WEIGHT OFHYDRATED ALUMINA.